fuel pump wiring expertise needed... (relay question)

[Xaeryan]

OK, I'm ADDING a fuel pump to my car for a water injection system I am making. The relay described in vfaq.com splices into the factory fuel pump wiring in order to power the relay's coil (terminal 85). What would be a good power source for me to do this, considering I don't want to splice into the current harness.

As an alternative, I was thinking of not attaching the relay coil wires (terminals 85 & 86) and just making the output wire 87a (the output terminal used when the coil is not active) but I think that would mean the fuel pump would be on even when the car isn't.
So what's a good source that's only on when the car is on (run or started, whichever).

If possible, a generic (non-Eclipse specific) source would be good, cause I'd like to do this on my other car, eventually, too.

 

[95talontsi]

this is what I did, ran a hard wire from the batt to the fuel pump, good thick wire then made a nice solid ground under a seat, my trigger is a wire that goes to the gauges fuse, when I turn on the car the acsesory switch turns on the fuel pump, I also put a switch inbetween the trigger wire as a cheap anti-theft device.

 

[Xaeryan]

ahh, power to a gauge or gauges fuse should work good... thanks!
...
But I just thought of how stupid I am - I could just skip triggering the coil, run power out of terminal 87a TO A SWITCH (which I'd need anyway to keep the system from constantly injecting water). I'd risk forgetting to turn the switch off when the car is shut off, but I think I'd notice the sound of the fuel pump.

Any opinions on this new idea?

 

[Xaeryan]

wait, I just thought of something in my idea above - what is the point of the relay, then?

I guess it would work the same if I just hardwired it without the relay.

 

[95talontsi]

no, the trigger to to relay is to allow you to use higher guage wire and to trigger it, I wired it to the gauges so I won't forget to tunr it off it automatically turns off when keys are out, but the switch allows the car not to be turned on when the keys are in if you want.

 

[Xaeryan]

No, I completely understand what you're saying, but in my case, I could skip the trigger and just hardwire the extra pump (no relay) and turn it on/off via a switch. In the future if I wanted to get more professional, I guess I could put a relay and trigger it off the gauge panel like you do, to eliminate the possibility of me forgetting to turn it off. I may have to do this anyway if the switch burns up like my last one did.

 

[DrZiplok]

I'm a bit confused as to what role the fuel pump plays in your plans for this system; fuel pumps are not designed for long-term exposure to water or alcohol, and I suspect you'll see rapid corrosion followed by either seal failure or jet clogging.

I suggest you head to the DSM_water_injection Yahoo! group and check out the many long, detailed discussions there.

You'll also find several people selling kits based on the low-end Shurflo setup on eBay; from my readings on the group you're going to want a pressure reservoir on top of the kit's contents.

HTH.

 

[Xaeryan]

DrZipLok - confusion well received... According to Bosch, their fuel pumps are stainless internally, eliminating corrosion. As for the seals, well I don't quite know yet.

Using a fuel pump and overflow reservoir pillaged from a junkyard, along with a NOS nozzle and some custom plumbing/wiring can save quite a bit, even over the budget systems. And holy crap are Aquamist systems expensive. $550 for stage 1, $900 for stage 2!!!!

 

[onegee]

pillage...o...cool word....sorry for hijacking ur thread